Yes, when I talk about C++ compiler speed I generally mean Clang, since it's a widely-available high-quality implementation with compiler speed as an explicit priority. In the context of Rust it's doubly relevant since they both use LLVM. Compiler speed wasn't an explicit priority for the Rust developers in the run-up to 1.0, but these days it's essentially top priority (hence the aforementioned middle end overhaul, though it has more benefits than just incremental recompilation), and the speed of the compiler has already more than doubled since 1.0.